How to Fit an Air Brick for Floor Ventilation
Fitting an Air Brick
Exterior air bricks are the traditional means of ventilating the space under suspended floors at ground level. Alterations to the house or garden may mean that the original bricks are no longer performing their function. As a general rule there should be an air brick every 2.5m (8ft) along an external wall. If there are less air bricks in the walls of your house, or if you have signs of mould or damp due to lack of air movement, you should consider fitting additional bricks. Air bricks come in a variety of sizes but the easiest to fit are the smaller ones, used here, which have the same overall dimensions as a common house brick.
Tools for the Job:
- cordless drill/driver
- club hammer & bolster
- protective gloves & goggles
- pointing trowel
- To install an additional air brick, or replace one that is missing, first select a suitable standard brick to remove, 2-2.5m (6-½ – 8ft) from the nearest existing air brick. It should also be at least one course below the damp-proof course and below the level of the floor inside. Drill lots of holes to break up the brick, using an electric drill with a large masonry bit.
- Remove the remainder of the brick with a club hammer and bolster chisel, taking great care not to damage the adjacent brickwork. Most of the mortar holding the brick in place will probably come away with the brick. Remove any remaining mortar so that you have a clean hole ready to receive the air brick.
- Mix up some mortar using 3 parts sand to 1 part cement Cut a couple of strips of timber 50mm (2in) long with a square section the same thickness as the existing mortar courses in the brick wall. Place the strips in the bottom of the hole and hold them in place with a little mortar. Damp down the new brick and spread mortar onto the top and ends.
- Slide in the brick, ensuring it stays flush with the existing brickwork. Check with a straightedge that the brick is not too far in or sitting proud. Work in additional mortar to the joint with a pointing trowel, if necessary. After about an hour when the mortar has just started to harden, finish with a jointing trowel.
When chopping out old bricks with a hammer and chisel, make sure you wear gloves to protect your hands and, more importantly, goggles to protect your eyes from flying chips.
Tips of the Trade
When pointing brickwork, leave the mortar to ‘go off’ a little before finishing. In this way you will not drag mortar out of the join and the finish will be smoother.